This invention relates to knock-down storage racks and more particularly to a locking connector for preventing the separation of the uprights from the shelves of a knock-down storage rack after they are interconnected.
Knock-down storage racks are well known and are in common use for storage in such places as warehouses, garages and basements. The racks are composed of columns or uprights and horizontal shelf-supporting beams. Usually the uprights have a number of spaced apart slots and the beams have teeth or studs. The beams are connected to the uprights by insertion of the teeth or studs into the slots of the uprights. The beams can be set at a desired level by appropriate choice of slots in which the teeth or studs are inserted.
Once the teeth or studs of the shelf-supporting beams are in the slots, the beams will remain secure so long as there is a downward force on the beams. Thus, if the beams are loaded, the storage rack will remain intact. If, however, an upward force is applied to the beams, the beams will separate from the uprights and the storage rack will come apart. It may also come apart when the beams are not loaded and a sideways force is applied to the rack.
Fork lift trucks are commonly used to load and unload heavy items on storage racks. Such items are usually placed on pallets so that there is space beneath them for the prongs of the fork lift. In unloading an item from the shelf-supporting beam, the operator of the truck may accidentally insert the prongs beneath the beam where the item is located and not into the pallet. When the operator lifts the prongs, the beam will rise with the load and the storage rack may come apart. When this happens, heavy items on the beams may fall onto the operator of the truck or any bystanders in the vicinity of the rack with resulting injury or, in extreme instances, death. Items on the rack may be also damaged in the fall.
It is known to provide locks for preventing the shelves from separating from the uprights once the storage rack is assembled. Examples of such locks are described in U.S. Pat. No. 5,938,367 and U.S. Pat. No. 6,155,441. Such locks frequently have a plunger which when activated, is within the same slot as a tooth or stud of a shelf where the plunger prevents the tooth or stud from withdrawing from the slot in the upright. The plunger is deactivated by withdrawing it from the slot so that the shelf may be separated from the upright.
A shortcoming of many such locks is that they are susceptible to accidental deactivation. Some, for example, become deactivated when they are rotated one quarter or one half turn. When such locks are accidentally struck, they may turn incrementally. If they are struck repeatedly, eventually they will rotate sufficiently to deactivate. Other locks are spring-loaded and activate and deactivate when they are pressed. They too can deactivate when accidentally struck.
Another shortcoming of such locks is that are susceptible to breakage if they are accidentally struck. In some cases, for example, the locks are held in position by tabs or ears which are riveted or welded in position. If such locks are accidentally struck by the prongs of a fork lift truck, the tabs may break off.
The locking connector of the subject invention resists deactivation when accidentally struck. The locking connector can only be opened or deactivated by means of a relatively large force. Preferably a tool such as a screw driver is required to apply such a force and in that case, the locking connector will not open unless an operator has such a tool and he uses it deliberately to open the connector. Accordingly a storage rack equipped with such a locking connector will not come apart should it be accidentally struck or should its shelf-supporting beams be accidentally raised when items are being unloaded from them.
The locking connector of the invention also resists breakage when struck. The locking connector, according to one embodiment, is contained within a housing which protects the locking connector. Hard blows may damage the housing but are unlikely to damage the lock.
Briefly, the locking connector of my invention interconnects a shelf-supporting beam and an upright of a knock-down storage rack. The locking connector is fixed to the beam and is removably connected to the upright. The locking connector has a plunger which is slidable between locking and unlocking positions. The plunger has a shank in which a recess is formed and which, when in the locking position, is within one of a number of openings formed in the upright with resulting locking of the upright to the connector. When the plunger is in the unlocking position, the shank is outside the opening thus allowing the upright to be separated from the connector. The lock includes a retainer which is biased by resilient means into the recess when the plunger is in the locking position and prevents the plunger from moving from the locking position unless a force, opposed to the bias of the retainer, is applied to the plunger to cause the retainer to withdraw from the recess.
A second embodiment of the locking connector has an outer wall having oppositely facing inner and outer surfaces and an aperture which is defined by an edge of the front wall. A casing extends outwardly from the front wall and has an inner end in which a groove is formed for receipt of the edge such that the margin of the front wall adjacent to the edge are within the groove. A plunger is confined within the casing and is slidable between a locking position in which the plunger extends though the aperture and one of the openings in the upright with resulting locking of the locking connector to the upright and an unlocking position in which the plunger is outside the opening. The locking connector has resilient means which biases the plunger into the locking position and which opposes movement of the plunger from the locking position unless a force, opposed to the bias of the resilient means, is applied to the plunger to cause the plunger to withdraw from the opening